@article{DAN_1991_316_4_a17,
     author = {B. T. Polyak and Ya. Z. Tsypkin},
     title = {Robust stability of linear discrete systems},
     journal = {Doklady Akademii Nauk},
     pages = {842--846},
     publisher = {mathdoc},
     volume = {316},
     number = {4},
     year = {1991},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1991_316_4_a17/}
}